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A new multidisk magnetorheological fluid actuator was proposed using the shear stress of magnetorheological fluid between rotating disks. The transmission torque was calculated based on the Bingham model, and the magnetic circuit was designed in accordance with electromagnetic theory. Then, a magnetostatic simulation was conducted to validate the designed magnetic circuit. Furthermore, an experimental study was performed to investigate the performance of the prototype. The results show that the transmission torque increases approximately linearly with the input current within the saturation range of magnetorheological fluid. Both the input current and the gap thickness have little influence on the dynamic response property of the proposed magnetorheological fluid actuator. Moreover, the temperature of magnetorheological fluid increases linearly with the time in the slip and loaded states, and the greater the slip power is, the faster the temperature rises. Furthermore, the temperature rise of magnetorheological fluid will result in the reductions of the torque transmission ability and the dynamic response speed. On the whole, the proposed multidisk magnetorheological fluid actuator has a higher torque capacity and a slightly slower dynamic response in comparison with the present magnetorheological devices. It is promising for applications in many high torque occasions. [ABSTRACT FROM AUTHOR]

Background: Compelling evidence has shown that the incidence of lumbar disc herniation (LDH) increases with age. In this study, retrospective clinical analysis of 601 cases of LDH has been conducted to investigate the role of age in the incidence of LDH in the elderly. The aim of the study is to investigate the relationship between the process of aging and the occurrence of LDH in old adults., Methods: Clinical cases (n = 601) of LDH were retrospectively analyzed., Results: The imaging examination with computed tomography and/or magnetic resonance imaging showed the occurrence of degeneration in LDH patients over 65 years of age. The most common site of LDH is toward the bottom of the spine at L4-L5 and/or L5-S1. The incidence of LDH drops with age in the elderly, especially after the age of 80 years. There is an obvious decrease in LDH in the elderly female., Conclusion: A decreasing incidence of LDH with aging occurs in the elderly. This investigation indicates that aging is not a contributor to the performance of LDH in the elderly although the incidence of LDH is proportional to age.

Objective: To evaluate the possibility of collateral outflow tract of arterial sclerosis obstruction (ASO) and the prospect of clinical application., Methods: The red emulsion was infused into the arteries of the above knee amputation of 10 fresh specimens. Then the pathological changes of the anterior tibial artery, posterior tibial artery and the popliteal artery, and the contribution of these bole artery branch were observed. From September 2005 to April 2007, 5 patients with ASO were treated, unilateral lower limb was involved in all cases. There were 3 males and 2 females, aged 68-81 years. The arteriography and Color Doppler ultrasound of lower limbs showed that the femoral artery and the popliteal artery and the branches had no development. The exploratory operation on the popliteal artery and the branches was carried out., Results: The walls of the anterior tibial artery, posterior tibial artery, and the popliteal artery were stiff and the lumens were filled with atheromatous plaque. The sural arteries opening to the bole artery was frequent. The collateral circulation at the knee perimeter was raritan rather affluent at the muscle group. All of the operations were successful, the skin temperature increased gradually after operation, and the degrees of blood oxygen saturation increased to 90%-100% at 6 hours from 0 before operation. After a follow-up of 3 to 12 months, the symptom improved obviously, rest pain disappeared, lower limb ulcer healed. The Color Doppler ultrasound showed that most of the blood flow at the anastomotic stoma ejected into bypass circuit, and the blood flow at the distally posterior tibial artery and anterior tibial artery was little., Conclusion: The collateral outflow tract construction is feasible, it is an effective path after clinical verification to solve the advanced stage ASO.